Unitary vacuum hold down apparatus for large and small record sheets

ABSTRACT

A noiseless unitary apparatus to retain small and large size record sheets in selected fixed positions on different parts of a perforated surface of a vacuum chamber by providing a wall within the chamber that No. 1 divides the chamber into two vacuum areas and that No. 2 has a restricted air passageway formed therein to reduce the flow of air between one vacuum area and the other while it is being drawn by a vacuum impeller through any of the perforated surfaces that are not covered by one of said record sheets.

[72] Inventor: Stephen H. Duncan, Denver, C010.

[73] Assignee: Honeywell Inc., Minneapolis, Minn.

[22] Filed: Aug. 21, 1970 [2 l] Appl. No.: 66,023

[52] US. Cl ..248/363, 355/73 [51] Int. Cl. ..G03b 27/60 [58] Field of Search ..248/362, 363; 355/73; 269/21 [56] References Cited UNITED STATES PATENTS 2,814,233 11/1957 Ananderr. ..248/363 1,954,753 4/1934 Glaser ..248/362 X United States A Patent [151 3,659,818

Duncan 14 1 May 2, 1972 541 UNITARY VACUUM HOLD DOWN 2,458,302 1 1949 Richardson ..269/2l x APPARATUS F LARG AND SMALL 2,855,653 10/1958 Kastenbein ..269/21 x RECORD SHEETS 488,925 12/1892 Marsh ..269/21 X Primary Examiner-Chancellor E. Harris Attorney-Arthur l-l. Swanson, Lockwood D. Burton and John Shaw Stevenson 1 [57] ABSTRACT A noiselessunitary apparatus to retain small and large size record sheets in selected fixed positions on different parts of a perforated surface of a vacuum chamber by providing a wall within the chamber that No. l divides the chamber into two vacuum areas and that No. 2 has a restricted air passageway formed therein to reduce the flow of air between one vacuum area and the other while it is being drawn by a vacuum impeller through any of the perforated surfaces that are not covered by one of said record sheets.

10 Claims, 2 Drawing Figures Patented May 2, 1972 INVENTOR. STEPHEN H. DUNCAN AGENT.

It is an object of the present invention to disclose a vacuum hold down apparatus for large and small size record sheets.

it is a more specificobject to disclose an apparatus of the aforementioned type for use in holding down a large and small sheet of graph paper or other material on which it is desired to make a record of a condition.

i It is another object of the present invention to provide a wall between two vacuum areas of a vacuum chamber having a restricted opening therein to allow air to be drawn from the first vacuum area through the restricted opening into the second vacuum area and to then be evacuated from this last mentioned area.

It is another object of the present invention to provide a plate that covers both areas of the vacuum chamber with a series of spaced apart apertures along a marginal edge portion thereof and along a portion of the plate that is adjacent the wall that divides the vacuum chamber into two areas to thereby enable different size sheets that are positioned on the top plate to be retained thereon-while the air in both vacuum areas of the vacuum chamber is being evacuated.

. It is another object of the present invention to provide a restriction between the two areas of the vacuum chamber to restrict the air that is being drawn from the atmosphere through the aforementioned marginal spaced apart apertured wall portions 36, 38, 40, 42 formed in the top plate that are uncovered when a sheet of smallersize than the size of the top plate of the vacuum chamber is placed thereon.

It is another object of the present invention to provide a vacuum chamber of the aforementioned type which requires a much smaller, quieter, less expensive motor driven vacuum fan than that required by presently available paper hold down units.

It is another object of the present invention to eliminate the annoying whistle that is inherent in presently available single vacuum chambers that do not use the previously mentioned unique wall structure that provides a restriction between two vacuum areas of a vacuum chamber. I s

More specifically, it is another object of the present invention to employ a wall to separate two vacuum areas of a vacuum chamber by'means of a restriction in order to provide a more effective'vacuum for holding down small sheets of paper on the top table portion of a vacuum chamber.

A better understanding of the present invention may be had from the following detailed description when read in connection with the accompanying drawings in which:

'FIG. 1 is an exploded view of a noiseless multi size sheet hold down apparatus ;and

F IG. 2 is an elevation view showing a cross-sectional view of the two vacuum areas of the vacuum chamber as viewed along the plane 22 ofFIG. 1.

F 1G. 1 shows the vacuum hold down apparatus for retaining small and large sheets as being comprised of a first plate 12 forming a top plate of a table 14. A suitable plate 16 forms a bottom plate of the table 14 and a gasket strip 18 preferably made of a suitable foam tape extends around the marginal edges of the top and bottom plates 14, 16 to form a vacuum chamber 20 of the hold down apparatus 10.

The vacuum chamber 20 is furtherprovided with two gasket Another series of uniformly spaced apart apertured wall portions 44, 46 and some of the apertured wall portion 36, 40 that are positioned so that they are aligned with the marginal portions of the small sheet of record paper that is placed on the top front and side surface portion of the table plate 12.

All of the apertured wall portions 36, 38, 40, 42 are positioned so that they are aligned with a marginal portion of a large sheet of record paper when it is placed on the top surface of the top plate 12 of the table 14.

Suitable marks, not shown, can be inscribed on the top surface of the plate 12 to aid the operator in placing a small or large record sheet, such as an 8 /2 inch X l 1 inches or 1 1 inch X 17 inch sheet, in its correct previously referred to position thereon. I

The gaskets 18, 22, 24 forming walls are fixedly connected by a suitable commercially available cementing material at their bottom surface to the top surface of the bottom plate 16 and extend a small'distance above the position shown for the gasket 18 in FIG. 2 before the top plate is brought into physical contact with these gaskets as shown in the last mentioned FIG. 2.

lt is possible in the aforementioned manner to therefore effect an air tight seal between the top surface of the gasket strips 18, 22, 24 and the bottom surface of the top plate l2 when plate 12 is placed in an assembled position on the top of these gaskets 18, 22, 24. v

The vacuum area 30 is shown as having a tube 48 forming an apertured wall connection to the inlet passageway 50 of a vacuum impeller unit 52 that is of any well known commercially available variety. The unit 52 contains a suitable motor driven vacuum fan that can be operated to withdraw a flow of air from the vacuum area 30 and to release it into the atmosphere by way of the outlet passageway 54.

From the aforementioned description it can be seen that when the marginal portion of a small sheet of record paper is placed in its correct position over the series of spaced apart apertured wall portions 44, 46 and the apertured wall portions 40, 36 that are shown on the front and right forward portions of the top plate 12 that the vacuum which is then applied by the impeller unit 52 will effect a holding down force'on the small sheet of paper.

It can also be seen that the restrictive passageway formed between the ends 32, 34 of the gaskets strips 22, 24 affords a way of reducing the rate at which the air that has been drawn through the remaining uncovered'apertures eg 38, 42 in the top plate 12 into the vacuum area, 28 can be passed into the vacuum area 30.

By reducing the air flow in the aforementioned manner it eliminates the undesired whistle that is inherent in present day record sheet hold down devices.

The air flow restricting affect that is afforded by these strips .22, 24 has the additional advantage over present day hold down devices in that the increase pressure differential that is created by the restricting ends 32, 34 of wall 26 will thus provide an unusually beneficial greater hold down force on a small record sheet when the lower and left marginal areas of such a sheet are aligned with the lower front and adjacent side of the top plate 12 as shown in FIG. 1.

strips 22, 24, preferably constructed of'a suitable foam tape that form an innerwall 26 within thevacuum chamber 20. This inner wall 26 not only divides the vacuum chamber 20 into two vacuum areas 28, 30 but also provide two end wall portions 32, 34 that form a restricted passageway between the vacuum areas 28 and 30. i

The top and bottom plates l2, 16 of the table 14 are constructed of a thin aluminum sheet material that is preferably one eighth of an inch thick.

A series of apertured wall portions Le, 36, 38 are shown passing through an upper marginal right and'left side portion of the top plate 12. The front and rear portions of the plate 12 are also shown as having a series of uniformly spaced apart apertured wall portions 40,42.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A vacuum hold down apparatus for retaining different size sheets in a fixed position on a perforated surface of a vacuum chamber, comprising a wall separating the chamber into two vacuum areas and forming a restricted passageway between said areas, a means to draw air from one of said areas through said restricted passageway into the other of said areas and out of said last mentioned area to atmospheric pressure, said restricted passageway being operable to produce a differential pressure across said vacuum areas to enhance the hold down force against the surface of a selected one of said sheets when it is placed on a part of the perforated surface of the vacuum chamber.

2. The hold down apparatus as defined in claim 1 wherein the restriction is positioned adjacent the means that is employed to draw the air out of one of said chambers.

3. The hold down apparatus as defined in claim 1 wherein the restricted passageway provides a means for effecting a silent flow of air through the exposed perforated areas of the vacuum chamber and between said different vacuum areas.

4. The hold down apparatus as defined in claim 1 wherein the wall separating the vacuum chamber into two areas extend between the inner bottom and inner top wall surfaces of the chamber.

5. The hold down apparatus as defined in claim 1 wherein the wall is constructed of gasket strips constructed of a foam type material.

6. The hold down apparatus as defined in claim 1 wherein the base of the wall separating the vacuum chamber into two areas is fixedly connected to the inner base of the vacuum chamber and the top of said wall is retained in compressed fluid tight engagement by an inner top surface of the vacuum chamber.

7. The hold down apparatus as defined in claim 1 wherein the perforations formed in the vacuum chamber wall are positioned to extend into and through peripheral portions of each of said vacuum areas.

8. The hold down apparatus as defined in claim 1 wherein the height of the vacuum areas extending between the top and bottom plates of the vacuum chamber are of substantially the same size as the restricted passageway in said wall.

9. The hold down apparatus as defined in claim 1 wherein a passageway is fonned in the bottom of said chamber to connect one of said vacuum areas with said air drawing means.

10. The hold down apparatus as defined in claim 1 wherein a passageway is formed in the bottom of said chamber adjacent said restricted passageway to connect one of said vacuum areas with the air drawing means. 

1. A vacuum hold down apparatus for retaining different size sheets in a fixed position on a perforated surface of a vacuum chamber, comprising a wall separating the chamber into two vacuum areas and forming a restricted passageway between said areas, a means to draw air from one of said areas through said restricted passageway into the other of said areas and out of said last mentioned area to atmospheric pressure, said restricted passageway being operable to produce a differential pressure across said vacuum areas to enhance the hold down force against the surface of a selected one of said sheets when it is placed on a part of the perforated surface of the vacuum chamber.
 2. The hold down apparatus as defined in claim 1 wherein the restriction is positioned adjacent the means that is employed to draw the air out of one of said chambers.
 3. The hold down apparatus as defined in claim 1 wherein the restricted passageway provides a means for effecting a silent flow of air through the exposed perforated areas of the vacuum chamber and between said different vacuum areas.
 4. The hold down apparatus as defined in claim 1 wherein the wall separating the vacuum chamber into two areas extend between the inner bottom and inner top wall surfaces of the chamber.
 5. The hold down apparatus as defined in claim 1 wherein the wall is constructed of gasket strips constructed of a foam type material.
 6. The hold down apparatus as defined in claim 1 wherein the base of the wall separating the vacuum chamber into two areas is fixedly connected to the inner base of the vacuum chamber and the top of said wall is retained in compressed fluid tight engagement by an inner top surface of the vacuum chamber.
 7. The hold down apparatus as defined in claim 1 wherein the perforations formed in the vacuum chamber wall are positioned to extend into and through peripheral portions of each of said vacuum areas.
 8. The hold down apparatus as defined in claim 1 wherein the height of the vacuum areas extending between the top and bottom plates of the vacuum chamber are of substantially the same size as the restricted passageway in said wall.
 9. The hold down apparatus as defined in claim 1 wherein a passageway is formed in the bottom of said chamber to connect one of said vacuum areas with said air drawing means.
 10. The hold down apparatus as defined in claim 1 wherein a passageway is formed in the bottom of said chamber adjacent said restricted passageway to connect one of said vacuum areas with the air drawing means. 